Quantum-Resistant DeFi: Building Post-Quantum Yield Farms Before IBM's Computer Ruins Your Day

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
import "./libraries/LatticeSignatures.sol";

/**
 * @title QuantumResistantYieldFarm
 * @dev A yield farming contract that uses post-quantum cryptography
 * @notice This contract survives the quantum apocalypse
 */
contract QuantumResistantYieldFarm is ReentrancyGuard {
    using LatticeSignatures for bytes32;
    
    // Post-quantum public key structure
    struct QuantumKey {
        bytes32[] latticeMatrix;  // Lattice-based public key
        uint256 dimension;        // Lattice dimension
        uint256 modulus;         // Lattice modulus
    }
    
    // User stake information with quantum-resistant proof
    struct UserStake {
        uint256 amount;
        uint256 timestamp;
        bytes quantumProof;      // Post-quantum signature proof
        QuantumKey userKey;      // User's quantum-resistant key
    }
    
    mapping(address => UserStake) public stakes;
    mapping(bytes32 => bool) public usedQuantumProofs;
    
    event QuantumStakeDeposited(address indexed user, uint256 amount, bytes quantumProof);
    event QuantumRewardsClaimed(address indexed user, uint256 rewards, bytes quantumProof);
}

/**
 * @dev Deposit tokens with quantum-resistant authentication
 * @param amount Amount to stake
 * @param quantumKey User's post-quantum public key
 * @param quantumProof Lattice-based signature proof
 */
function quantumStake(
    uint256 amount,
    QuantumKey calldata quantumKey,
    bytes calldata quantumProof
) external nonReentrant {
    // Verify the quantum-resistant signature
    bytes32 messageHash = keccak256(abi.encodePacked(
        msg.sender,
        amount,
        block.timestamp,
        address(this)
    ));
    
    // Check if this proof was already used (prevent replay attacks)
    bytes32 proofHash = keccak256(quantumProof);
    require(!usedQuantumProofs[proofHash], "Quantum proof already used");
    
    // Verify lattice-based signature
    require(
        LatticeSignatures.verifyLatticeSignature(
            messageHash,
            quantumProof,
            quantumKey
        ),
        "Invalid quantum signature"
    );
    
    // Mark proof as used
    usedQuantumProofs[proofHash] = true;
    
    // Transfer tokens (using quantum-resistant verification)
    IERC20(stakingToken).transferFrom(msg.sender, address(this), amount);
    
    // Update user stake with quantum-resistant data
    stakes[msg.sender] = UserStake({
        amount: stakes[msg.sender].amount + amount,
        timestamp: block.timestamp,
        quantumProof: quantumProof,
        userKey: quantumKey
    });
    
    emit QuantumStakeDeposited(msg.sender, amount, quantumProof);
}

/**
 * @dev Calculate and distribute rewards with quantum-resistant verification
 * @param quantumProof New quantum signature for claiming rewards
 */
function claimQuantumRewards(bytes calldata quantumProof) external nonReentrant {
    UserStake storage userStake = stakes[msg.sender];
    require(userStake.amount > 0, "No stake found");
    
    // Calculate rewards (same logic, quantum-resistant verification)
    uint256 stakingDuration = block.timestamp - userStake.timestamp;
    uint256 rewards = calculateRewards(userStake.amount, stakingDuration);
    
    // Create message for quantum signature verification
    bytes32 rewardMessage = keccak256(abi.encodePacked(
        msg.sender,
        rewards,
        block.timestamp,
        "CLAIM_REWARDS"
    ));
    
    // Verify quantum-resistant signature for reward claim
    require(
        LatticeSignatures.verifyLatticeSignature(
            rewardMessage,
            quantumProof,
            userStake.userKey
        ),
        "Invalid quantum reward signature"
    );
    
    // Prevent quantum signature replay attacks
    bytes32 proofHash = keccak256(quantumProof);
    require(!usedQuantumProofs[proofHash], "Quantum proof already used");
    usedQuantumProofs[proofHash] = true;
    
    // Distribute rewards
    IERC20(rewardToken).transfer(msg.sender, rewards);
    
    // Update timestamp for next reward calculation
    userStake.timestamp = block.timestamp;
    userStake.quantumProof = quantumProof;
    
    emit QuantumRewardsClaimed(msg.sender, rewards, quantumProof);
}

// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;

library LatticeSignatures {
    // Lattice parameters (simplified for demonstration)
    uint256 constant LATTICE_DIMENSION = 512;
    uint256 constant LATTICE_MODULUS = 8380417; // Prime modulus
    uint256 constant SIGNATURE_BOUND = 2**19;   // Signature bound
    
    /**
     * @dev Verify a lattice-based signature (simplified implementation)
     * @param message Message that was signed
     * @param signature The lattice-based signature
     * @param publicKey The quantum-resistant public key
     * @return isValid True if signature is valid
     */
    function verifyLatticeSignature(
        bytes32 message,
        bytes calldata signature,
        QuantumResistantYieldFarm.QuantumKey calldata publicKey
    ) internal pure returns (bool isValid) {
        // Simplified lattice signature verification
        // In production, use a proper lattice crypto library
        
        // Step 1: Decode signature components
        (bytes32[] memory signatureVector, uint256 nonce) = abi.decode(
            signature,
            (bytes32[], uint256)
        );
        
        // Step 2: Verify signature dimension matches public key
        if (signatureVector.length != publicKey.dimension) {
            return false;
        }
        
        // Step 3: Check signature bound (prevent forgery)
        for (uint256 i = 0; i < signatureVector.length; i++) {
            uint256 component = uint256(signatureVector[i]);
            if (component >= SIGNATURE_BOUND) {
                return false;
            }
        }
        
        // Step 4: Verify lattice equation: A * s = H(m) + e (mod q)
        // Where A is public key matrix, s is signature, H(m) is hashed message, e is error
        bytes32 computedHash = computeLatticeVerification(
            publicKey.latticeMatrix,
            signatureVector,
            message,
            nonce
        );
        
        // Step 5: Check if the lattice equation holds
        return computedHash == message;
    }
    
    /**
     * @dev Compute lattice verification (simplified)
     * @notice This is a simplified version for demonstration
     */
    function computeLatticeVerification(
        bytes32[] calldata publicMatrix,
        bytes32[] memory signature,
        bytes32 message,
        uint256 nonce
    ) internal pure returns (bytes32 result) {
        // Simplified lattice computation
        // In production, implement proper lattice arithmetic
        
        uint256 accumulator = 0;
        for (uint256 i = 0; i < publicMatrix.length && i < signature.length; i++) {
            accumulator = addmod(
                accumulator,
                mulmod(uint256(publicMatrix[i]), uint256(signature[i]), LATTICE_MODULUS),
                LATTICE_MODULUS
            );
        }
        
        // Combine with message hash and nonce
        result = keccak256(abi.encodePacked(accumulator, message, nonce));
    }
}

// quantum-resistant-client.js
import { LatticeKeyGenerator } from './crypto/lattice-keys.js';
import { QuantumSigner } from './crypto/quantum-signer.js';

class QuantumResistantDeFiClient {
    constructor(web3Provider, contractAddress) {
        this.web3 = web3Provider;
        this.contract = new this.web3.eth.Contract(ABI, contractAddress);
        this.keyGenerator = new LatticeKeyGenerator();
        this.quantumSigner = new QuantumSigner();
    }
    
    /**
     * Generate quantum-resistant key pair for user
     * @returns {Object} Key pair with public and private components
     */
    async generateQuantumKeys() {
        console.log('🔐 Generating quantum-resistant keys...');
        
        const keyPair = await this.keyGenerator.generateLatticeKeys({
            dimension: 512,
            modulus: 8380417,
            securityLevel: 128 // bits of post-quantum security
        });
        
        // Store private key securely (never send to blockchain)
        this.storePrivateKeySecurely(keyPair.privateKey);
        
        return {
            publicKey: {
                latticeMatrix: keyPair.publicKey.matrix,
                dimension: keyPair.publicKey.dimension,
                modulus: keyPair.publicKey.modulus
            },
            keyId: keyPair.keyId
        };
    }
    
    /**
     * Stake tokens with quantum-resistant authentication
     * @param {string} amount Amount to stake
     * @param {Object} quantumKeys User's quantum-resistant keys
     */
    async stakeWithQuantumSecurity(amount, quantumKeys) {
        try {
            console.log('🚀 Initiating quantum-resistant staking...');
            
            const userAddress = await this.web3.eth.getAccounts()[0];
            const timestamp = Math.floor(Date.now() / 1000);
            
            // Create message to sign
            const message = this.web3.utils.soliditySha3(
                { type: 'address', value: userAddress },
                { type: 'uint256', value: amount },
                { type: 'uint256', value: timestamp },
                { type: 'address', value: this.contract.options.address }
            );
            
            // Generate quantum-resistant signature
            const quantumSignature = await this.quantumSigner.signMessage(
                message,
                quantumKeys.privateKey
            );
            
            // Execute staking transaction
            const tx = await this.contract.methods.quantumStake(
                amount,
                quantumKeys.publicKey,
                quantumSignature
            ).send({ from: userAddress });
            
            console.log('✅ Quantum-resistant stake successful:', tx.transactionHash);
            return tx;
            
        } catch (error) {
            console.error('❌ Quantum staking failed:', error);
            throw error;
        }
    }
    
    /**
     * Claim rewards with quantum-resistant verification
     * @param {Object} quantumKeys User's quantum-resistant keys
     */
    async claimQuantumRewards(quantumKeys) {
        const userAddress = await this.web3.eth.getAccounts()[0];
        
        // Calculate expected rewards
        const userStake = await this.contract.methods.stakes(userAddress).call();
        const rewards = await this.calculateExpectedRewards(userStake);
        
        // Create reward claim message
        const rewardMessage = this.web3.utils.soliditySha3(
            { type: 'address', value: userAddress },
            { type: 'uint256', value: rewards },
            { type: 'uint256', value: Math.floor(Date.now() / 1000) },
            { type: 'string', value: 'CLAIM_REWARDS' }
        );
        
        // Generate quantum signature for reward claim
        const quantumProof = await this.quantumSigner.signMessage(
            rewardMessage,
            quantumKeys.privateKey
        );
        
        // Claim rewards
        return await this.contract.methods.claimQuantumRewards(quantumProof)
            .send({ from: userAddress });
    }
}

// Usage example
const client = new QuantumResistantDeFiClient(web3, CONTRACT_ADDRESS);

// Generate quantum-resistant keys (do this once per user)
const quantumKeys = await client.generateQuantumKeys();

// Stake with quantum security
await client.stakeWithQuantumSecurity('1000000000000000000', quantumKeys);

// Claim rewards
await client.claimQuantumRewards(quantumKeys);

// Optimize gas usage for large quantum signatures
contract GasOptimizedQuantumFarm {
    // Use packed structs to reduce storage costs
    struct PackedQuantumStake {
        uint128 amount;        // Sufficient for most token amounts
        uint64 timestamp;      // Unix timestamp fits in uint64
        uint64 keyHash;        // Hash of full quantum key for verification
    }
    
    // Store full quantum proofs in IPFS, only store hashes on-chain
    mapping(address => PackedQuantumStake) public packedStakes;
    mapping(bytes32 => string) public quantumProofIPFS; // IPFS hash storage
    
    function stakeWithIPFSProof(
        uint256 amount,
        string calldata ipfsHash,
        bytes32 proofHash
    ) external {
        // Verify proof hash matches IPFS content (implement off-chain verification)
        require(verifyIPFSProofHash(ipfsHash, proofHash), "Invalid IPFS proof");
        
        // Store compact version on-chain
        packedStakes[msg.sender] = PackedQuantumStake({
            amount: uint128(amount),
            timestamp: uint64(block.timestamp),
            keyHash: uint64(uint256(proofHash))
        });
        
        // Store full proof reference
        quantumProofIPFS[proofHash] = ipfsHash;
    }
}

// test/quantum-resistant-tests.js
const { expect } = require('chai');
const { ethers } = require('hardhat');

describe('QuantumResistantYieldFarm', function() {
    let farm, owner, user1, user2;
    let mockQuantumKeys;
    
    beforeEach(async function() {
        [owner, user1, user2] = await ethers.getSigners();
        
        const QuantumFarm = await ethers.getContractFactory('QuantumResistantYieldFarm');
        farm = await QuantumFarm.deploy();
        
        // Generate mock quantum keys for testing
        mockQuantumKeys = generateMockQuantumKeys();
    });
    
    it('should verify valid quantum signatures', async function() {
        const amount = ethers.utils.parseEther('100');
        const timestamp = Math.floor(Date.now() / 1000);
        
        // Create valid quantum signature
        const message = ethers.utils.solidityKeccak256(
            ['address', 'uint256', 'uint256', 'address'],
            [user1.address, amount, timestamp, farm.address]
        );
        
        const quantumSignature = await createMockQuantumSignature(
            message,
            mockQuantumKeys.privateKey
        );
        
        // Test staking with quantum signature
        await expect(
            farm.connect(user1).quantumStake(
                amount,
                mockQuantumKeys.publicKey,
                quantumSignature
            )
        ).to.not.be.reverted;
    });
    
    it('should reject invalid quantum signatures', async function() {
        const amount = ethers.utils.parseEther('100');
        const invalidSignature = '0x1234'; // Invalid signature
        
        await expect(
            farm.connect(user1).quantumStake(
                amount,
                mockQuantumKeys.publicKey,
                invalidSignature
            )
        ).to.be.revertedWith('Invalid quantum signature');
    });
    
    it('should prevent quantum signature replay attacks', async function() {
        const amount = ethers.utils.parseEther('100');
        const quantumSignature = await createValidQuantumSignature(user1, amount);
        
        // First use should succeed
        await farm.connect(user1).quantumStake(
            amount,
            mockQuantumKeys.publicKey,
            quantumSignature
        );
        
        // Second use should fail
        await expect(
            farm.connect(user1).quantumStake(
                amount,
                mockQuantumKeys.publicKey,
                quantumSignature
            )
        ).to.be.revertedWith('Quantum proof already used');
    });
});

contract HybridQuantumFarm {
    enum SignatureType { TRADITIONAL, QUANTUM_RESISTANT }
    
    function stake(
        uint256 amount,
        SignatureType sigType,
        bytes calldata signature,
        bytes calldata publicKey
    ) external {
        if (sigType == SignatureType.TRADITIONAL) {
            // Verify ECDSA signature (current method)
            verifyECDSASignature(amount, signature);
        } else {
            // Verify quantum-resistant signature
            verifyQuantumSignature(amount, signature, publicKey);
        }
        
        // Rest of staking logic remains the same
        processStake(amount);
    }
}

contract IncentivizedQuantumMigration {
    uint256 public constant QUANTUM_BONUS = 1050; // 5% bonus for quantum users
    uint256 public constant TRADITIONAL_RATE = 1000; // Base rate
    
    function calculateRewards(address user) public view returns (uint256) {
        UserStake storage stake = stakes[user];
        uint256 baseRewards = stake.amount * stakingDuration / REWARD_PERIOD;
        
        // Bonus for quantum-resistant users
        if (stake.signatureType == SignatureType.QUANTUM_RESISTANT) {
            return baseRewards * QUANTUM_BONUS / 1000;
        }
        
        return baseRewards * TRADITIONAL_RATE / 1000;
    }
}